Inter Solar Systems [P] Ltd. Manufactures Forced Flow Type Solar Water Heating System. Inter Solar Systems [P] Ltd. Is an ISO 9001:2000 certified company. Inter Solar Systems [P] Ltd. Supplies ISI marked solar energy products. Forced Flow Type Solar Water Heating System is capable of heating up to 85 degree C. In Forced Flow Type Solar Water Heating System, the cold water from the cold water tank is transferred to the collector by a pump. The water from the solar panels is transferred to the insulated storage tank by hot water outlet. The further distribution of hot water is done.